A team at the Wake Forest Institute for Regenerative Medicine at Winston-Salem in North Carolina has developed a new bioprinter, called ITOP: Integrated Tissue and Organ Printing System. This 3D printer creates viable human organs that are strong enough to survive surgical transplantation.

Up until now, most 3D-printed organs and tissues have not been large enough or stable enough to implant in humans. But ITOP produces viable structures that have been tested in mice and rats; Wake Forest’s study has even been backed by the U.S. Armed Forces Institute for Regenerative Medicine. That’s because ITOP has the potential to save the lives of wounded soldiers.

A bioprinter, described today in Nature Biotechnology, was used to make ear, bone, and muscle structures out of plastic-like materials and living cells belonging either to humans, rabbits, rats, or mice. The cells survived the printing process—a feat that has not been easy to accomplish in the past—and the structures were stable enough to be successfully implanted in rodents, the researchers report. If the technology works in humans the way it has in animals, doctors may soon find themselves using bioprinters to produce replacement cartilage and bone for people who have been injured, using a patient’s own cells.

ITOP makes the organs by layering patterns of biodegradable, plastic-like materials and water-based gels containing stem cells. Once transplanted, these organs could be colonized by human blood vessels (their plastic-like elements having degraded), and their self-sustaining regenerative processes can begin. Wake Forest’s most significant achievement, though, may be the ITOP organs’ ability to withstand implantation. The team invented a temporary polymer outer shell to keep structures intact during this process. They also added tiny channels to the printed tissues that help carry nutrients, water, and oxygen to the living cells. Here’s NOVA Next contributor Jenny Morber, reporting last year:

In many ways, the challenges of 3D organ printing mirror those of organ transplantation. As Nathan from Gift of Life points out, “When taken from a deceased person, tissues can be collected 24 hours after the heart stops, but organs need a blood supply.” Without vasculature, cells do not receive nutrients and oxygen or excrete wastes beyond a thickness of a few layers. “One of the greatest challenges is ensuring that printed structures have an adequate supply of nutrients and oxygen until they can integrate with the body,” says Dr. Anthony Atala, the director of the Wake Forest Institute for Regenerative Medicine.

So far, Atala’s team has observed nerve formation after two weeks in muscle tissue that they inserted in rats. They’ve also printed human-sized ears and documented the formation of cartilage tissue after two months in mice. These and other tests are showing the ITOP’s great promise and the dawn of a new era in personalized medicine.